1. Field
The following description generally relates to vacuum-driven fluid delivery devices.
2. Description of Related Art
A vacuum-driven fluid delivery device outputs fluid under a force generated by a vacuum in a vacuum chamber. An example of a vacuum-driven fluid delivery device is disclosed in U.S. Pat. No. 8,973,847 by lammatteo and Bicej, issued on Mar. 10, 2015, the entire disclosure of which is incorporated herein by reference for all purposes. When such a fluid delivery device remains unused with a volume of vacuum in the vacuum chamber (i.e., in a “charged” state), the fluid delivery device is susceptible to loss of some or all of the volume of the vacuum over time. That is, external gases permeate into the vacuum chamber over time and replace at least a portion of the vacuum chamber that was previously occupied by the vacuum, thereby reducing the maximum vacuum volume of the vacuum chamber. Such a reduction in the maximum vacuum volume reduces the maximum duration of fluid output from the fluid delivery device.
Accordingly, it is desirable to provide a vacuum-driven fluid delivery device that prevents undesirable loss in maximum vacuum volume of the vacuum chamber during storage of the device in a charged state.